After years of planning and delays, the Albany Convention Center Authority is expected to approve the purchase of the first piece of land needed to build a downtown convention center.

The authority is scheduled to vote July 31 to spend $469,673 on a nearly half-acre parcel near the Greyhound bus station that the company uses as a storage yard.

The storage yard, which sits behind a chain link fence, is bounded by Green, Division and Dallius streets.

The price is less than the appraised and assessed values for the property, but matches Greyhound’s book value, said Duncan Stewart, executive director of the authority.

Greyhound has already approved the sale. The bus company will continue using the storage yard until construction begins on the convention center. The bus station itself will remain unless the convention center is built and then expanded in the future.

The transaction is important for symbolic and practical reasons.

This will be the first time the Convention Center Authority has acquired land to build the roughly $250 million convention center, a project that has been talked about, studied and debated in the city for 15 years.

The parcel sits in the middle of what someday would be a 60,000-square-foot exhibition hall, the centerpiece of the 266,000-square-foot facility off Hudson Avenue.

“It’s very significant because of the size and location within the footrpint of the building,” Stewart said.

The remainder of the convention center would include another 25,000 square feet of exhibition space, 20,000 square feet of divisible meeting rooms, a 10,000- square-foot “junior” ballroom and the kitchen, lobbies, mechanical/electrical areas and storage.

None of that will be built without the blessing of Gov. David Paterson.

The governor, who controls the purse strings, agreed to release $10 million to the authority earlier this year so it could acquire property and do other preliminary work.

He has not yet approved spending the remainder of the $75 million that was set aside for the project three years ago by former Gov. George Pataki.

Convention Center authority officials hope the land purchase demonstrates to the governor that the convention center has momentum. Negotiations are continuing with owners of the other public and privately held land. About six acres are needed.

The Mercer Cos., Omni Development, and Greyhound own or control the bulk of the private property.

Meanwhile, the state Legislature approved a critical source of funding for the authority when it voted this month to reinstate the 3 percent hotel bed tax in Albany County.

Provided county legislators also approve the tax, the authority will again receive about $1 million annually from the bed tax.